You may be getting an unwanted jolt from that morning decaf.Coffee sleuths from Consumer Reports recently tested cups of decaf ordered at Dunkin’ Donuts, Starbucks, Seattle’s Best Coffee, 7-Eleven, McDonald’s and Burger King. They visited six locations of each chain, evaluating 36 cups of decaf in all. A regular cup of coffee has from 85 to 100 milligrams of caffeine. Most of the 10- to 12-ounce decafs tested had less than five milligrams, the magazine reports in its November issue. But one decaf from Dunkin’ Donuts contained 32 milligrams — about the same amount in 12 ounces of Coca-Cola Classic. A cup of Seattle’s Best was found to contain 29 milligrams of caffeine, while a tall Starbucks decaf packed 21 milligrams. Results varied at each chain, but the magazine found that the decaf at McDonald’s consistently had the lowest levels of caffeine. [...]